tx-generator: make it buildable in leios-prototype

[mkoura]

Description

Fixes for building tx-generator binary in the leios-prototype branch.

• Codecs gained cLeiosNotifyCodec/cLeiosFetchCodec fields; extend myCodecs signature with two extra ByteString params.
• byteLimitsKeepAlive no longer takes a size function; drop (const 0).
• runPeer/runPeerWithLimits now return Maybe (Reception bytes); update kaClient return type and import Reception from Network.Mux.Channel.

The nix build .#tx-generator -o nix-build-tx-gen works with the fixes.

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. These may include:
  • golden tests
  • property tests
  • roundtrip tests
  • integration tests
    See Running tests for more details
• Any changes are noted in the CHANGELOG.md for affected package
• The version bounds in .cabal files are updated
• CI passes. See note on CI. The following CI checks are required:
  • Code is linted with hlint. See .github/workflows/check-hlint.yml to get the hlint version
  • Code is formatted with stylish-haskell. See .github/workflows/stylish-haskell.yml to get the stylish-haskell version
  • Code builds on Linux, MacOS and Windows for ghc-9.6 and ghc-9.12
• Self-reviewed the diff

[ch1bo]

I think this should be already included in the leios-prototype-remake in IntersectMBO/cardano-ledger#5839? If not, rebase this onto the remake and let's merge it into that. Our plan is to be fast-forwarding leios-prototype into that leios-prototype-remake branch very soon